Predators that are keystone species can maintain species diversity in a community if they
a. Competitively exclude other predators
b. Prey on the community's dominant species
c. Reduce the number of disruptions in the community
d. Prey only on the least abundant species in the community

Based on the intermediate disturbance hypothesis, a community's species diversity is increased by

a. Frequent massive disturbance

b. Stable conditions with no disturbance

c. Moderate levels of disturbance

d. Human intervention to eliminate disturbance

According to the island equilibrium model, species richness would be greatest on an island that is

a. Large and remote

b. Small and remote

c. Large and close to a mainland

d. Small and close to a mainland

Pioneer species tend to have high ________ and lower survivorship.

According to the generalized species-area curve, when habitat is reduced to 50% of its original size, approximately

a. 10%

b. 25%

c. 50%

d. 90%

Food chains are sometimes short because

a. Only a single species of herbivore feeds on each plant species.

b. Local extinction of a species causes extinction of the other species in its food chain.

c. Most of the energy in a trophic level is lost as energy passes to the next higher level.

d. Most producers are inedible.

Which of the following best illustrates ecological succession?

a. A mouse eats seeds, and an owl eats the mouse.

b. Decomposition in soil releases nitrogen that plants can use.

c. Grasses grow in a deserted field, followed by shrubs and then trees.

d. Imported pheasants increase in numbers, while local quail disappear.

Which of the following could qualify as a top-down control on a grassland community?

a. Limitation of plant biomass by rainfall amount

b. Influence of temperature on competition among plants

c. Influence of soil nutrients on the abundance of grasses versus wildflowers

d. Effect of grazing intensity by bison on plant species diversity